chore(package): update dependencies

http://greenkeeper.io/

package.json

@@ -26,10 +26,10 @@
     "for-own": "^0.1.3",
     "gulp": "^3.8.11",
     "gulp-coveralls": "^0.1.3",
-    "gulp-istanbul": "^0.6.0",
+    "gulp-istanbul": "^0.10.2",
     "gulp-mocha": "^2.0.0",
-    "rescale": "^6.1.0",
+    "rescale": "^8.0.1",
     "rimraf": "^2.3.2",
-    "should": "^5.0.0"
+    "should": "^7.1.1"
   }
 }